--First data reported in the field from the largest
randomized study to date--

--Study of STX209 to advance --

CAMBRIDGE, Mass.--(BUSINESS WIRE)--Jul 26, 2010 - Seaside
Therapeutics, Inc. announced today data from the largest
randomized, placebo-controlled study conducted to date in
individuals with fragile X syndrome. In a Phase 2 study of STX209,
clinically meaningful improvements on global and specific
neurobehavioral outcomes were observed in the general study
population. The improvements were statistically significant in
pediatric patients with more severe impairments in sociability -- a
core symptom of fragile X syndrome. STX209 is a selective
gamma-amino butyric acid type B (GABA-B) receptor agonist. The
results were presented in a podium presentation at the National
Fragile X Foundation's 12th International Fragile X Conference in
Michigan on Saturday, July 24, 2010 by investigators Elizabeth
Berry-Kravis, MD, PhD, Professor of Pediatrics, Neurological
Sciences and Biochemistry at Rush University Medical Center in
Chicago, Illinois and Randi Hagerman, MD, Medical Director,
M.I.N.D. Institute, Professor, Endowed Chair in Fragile X Research,
School of Medicine, University of California, Davis, in Sacramento,
California. Seaside continues to conduct additional analyses of
other outcome measures and biomarker data sets and intends to
submit full results for publication.

“A majority of the patients enrolled in the STX209 study
are participating in the ongoing open-label extension study and are
continuing to benefit from treatment with STX209,” said Dr.
Randi Hagerman. “Physicians and parents are reporting
increased sociability and communication and decreased outbursts and
tantrums. In several cases, patients have been successfully
withdrawn from other medications, including mood stabilizers,
anti-depressants and, most importantly, anti-psychotics—a
significant benefit for patients given the severe side effects
associated with this particular class of drug. It is my hope that,
with further study, STX209 may be able to play a much needed role
in improving the symptoms of fragile X syndrome and help patients
and their families achieve an improved quality of life.”

“Seaside Therapeutics conducted one of the most
comprehensive studies to date in a neurodevelopmental disorder and
achieved our goal of increasing knowledge regarding potential
efficacy measures in patients with fragile X syndrome,” said
Randall L. Carpenter, MD, President and Chief Executive Officer of
Seaside Therapeutics. “The study assessed a broad range of
behavioral and cognitive outcomes and, as would be expected in a
study of this scope, we observed significant benefit in some key
areas but not in others. We believe the depth of data coming from
this study will be of tremendous benefit for the field and will
inform ongoing discussions with both clinicians and the FDA to
confirm the most appropriate outcomes to measure efficacy in
individuals with fragile X syndrome. We look forward to initiating
late-stage clinical trials of STX209 later this year after
discussions with the FDA.”

Study Results:

Per Protocol Population:

In the per protocol population of 54 patients, STX209
consistently showed a positive trend for all global measures,
including investigators' assessments of Clinical Global Impressions
of Improvement (CGI-I) (p=0.18) and Severity (CGI-S) (p<0.10)
and investigator (p<0.10) and caregiver treatment preference
(p<0.10). One third of the treatment population was noted as
“Much improved” or “Very much improved” on
the CGI-I scale, whereas placebo scores were clustered around
“No change.” While improvement was noted on the
Irritability subscale of the Aberrant Behavior Checklist (ABC-I),
the study's primary endpoint, the magnitude was comparable to that
observed on placebo and did not achieve statistical
significance.

Low Sociability Population:

Social withdrawal is a core symptom of fragile X syndrome. In
the STX209 study, 15 pediatric patients presented with more severe
impairments in sociability at baseline. In these patients, STX209
treatment was associated with statistically significant
improvements on all global measures, including CGI-I (p<0.01),
CGI-S (p<0.05), clinician (p<0.01) and parent/caregiver
(p<0.01) preference, as well as improvements on two widely-used
measures of social function—the Aberrant Behavior
Checklist-Social Withdrawal (ABC-SW, p=0.05) and the Vineland Play
and Leisure (p<0.10). In the responder analysis, responders were
defined as those subjects with a score of “Very much”
or “Much improved” on the CGI-I scale and with a 25%+
improvement on the ABC-SW. When applying these rigorous criteria,
more than 50% of subjects showed a positive response while taking
STX209, versus just 13% on placebo (p=0.05).

Safety Overview:

STX209 was well tolerated, and there were no metabolic side
effects observed. The most common adverse events in subjects
receiving STX209 were upper respiratory infections (13%), sedation
(8%) and headache (8%), compared to 10%, 2% and 2%, respectively,
while receiving placebo. Three patients withdrew due to adverse
events, including one serious adverse event on the STX209 arm and
two adverse events on placebo. The serious adverse event of
worsening irritability and hospitalization occurred during taper of
STX209 in a patient who had a positive clinical response while
taking the drug.

Trial Design:

The STX209 trial was a Phase 2 randomized, double-blind,
placebo-controlled, two-period crossover study in 63 patients with
fragile X syndrome. The study enrolled 24 patients ages 6-11 years,
22 patients ages 12-17 years and 17 patients ages 18-40 years. The
objective of the study was to explore the safety and efficacy of
STX209 in patients with fragile X syndrome. A broad range of
behavioral and cognitive outcomes were included in the study design
to add to the Company's knowledge of potential efficacy measures in
patients with fragile X syndrome.

Key inclusion/exclusion criteria included a fragile X full
mutation and a minimum severity on the ABC-I scale. Participants
were limited to no more than three psychoactive medications, with
stable dosing for four weeks prior to entering the study.

Dosing was conducted as a flexible titration, every three days,
to the optimal titrated dose (OTD). The starting dose was 1 mg
twice a day and was gradually increased up to 10 mg twice a day for
subjects ‰¤11 years and up to 10 mg three times a day
for subjects ‰¥12 years. OTD was continued for the
remainder of the four-week treatment period, with a taper after
completion of the four-week period.

About STX209:

Recent discoveries by Mark Bear, PhD, Professor of Neuroscience,
M.I.T, Investigator, Howard Hughes Medical Institute, and Seaside's
scientific founder, have revealed a molecular pathway, the mGluR5
signaling cascade, that is disrupted in fragile X syndrome. With
this knowledge, further research has provided insights for
developing novel medications to correct the function of this
pathway, which Seaside believes may extend beyond fragile X
syndrome into a number of other developmental disorders, including
autism.

Fragile X syndrome is the most common inherited form of mental
impairment and the most common known cause of autism. According to
the Centers for Disease Control, an estimated one in 4,000 males
and one in 6,000 to 8,000 females have fragile X syndrome. Fragile
X syndrome is caused by a mutation of a single gene, the Fragile X
mental retardation 1 (FMR1) gene, on the X chromosome. The FMR1
gene produces a protein needed for normal brain development.
Individuals with fragile X syndrome lack this protein and, as a
result, exhibit a number of behavioral and physical symptoms,
including mental and developmental impairment, attention deficit
and hyperactivity, autistic behaviors, anxiety, seizures and
characteristic facial appearance.

About Seaside Therapeutics:

Seaside Therapeutics, Inc. is creating novel drug treatments to
correct or improve the course of fragile X syndrome, autism and
other neurodevelopmental disorders. The Company is dedicated to
translating breakthrough discoveries in neurobiology into
therapeutics that improve the lives of patients and their families.
For more information please visit
www.seasidetherapeutics.com.